请填写完整单词 In the early 20th century, charge a______ became popular. With automobiles and airplanes, people now had the o______ to travel to a variety of stores for their shopping needs. In an e______ to capture customer l_______, many stores and gas stations began to offer charge accounts for their customers which could be a________ by a card. Unfortunately, people needed to carry d________ of these cards if they were to do a day of shopping.